The objective of this study is to assess the ability of subcutaneous Gonal-F in combination with intramuscular human gonadotrophin (hCG) to initiate spermatogenesis and achieve a density of mature sperm cells of > 1.5 million per ml in men with idiopathic hypogonadotropic hypogonadism. This study will also determine the safety and tolerance of Gonal-F administered in combination with hCG for 18 months in this patient population.